Liquid crystal display device, its mounting structure and electronic device

ABSTRACT

Liquid crystal display device wherein, in addition to the semiconductor chip for liquid crystal drive, a liquid crystal drive circuit or all or some of the other electronic components required for the liquid crystal display control circuit are mounted on one circuit board made from regular hard substrate materials, and the output terminals of said circuit board are connected directly to the liquid crystal cell using an anisotropic conductive film or other known means. The input terminals of the circuit board are connected directly to the terminals of the main unit substrate of the electronic device wherein the liquid crystal display device is installed via a flexible cable, a rubber connector made from conductive rubber or an anisotropic conductive film, or by solder or adhesive. The liquid crystal display device can be secured in place by sandwiching it between the case of the electronic device and the main unit substrate attached to it, in which case the rubber connector between the input terminals of the circuit board and the terminals of the main unit substrate is retained in a compressed state.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to the structure of a liquid crystal displaydevice and to the structure for mounting the liquid crystal displaydevice in a main unit or various devices, and it also relates to anelectronic device equipped with the liquid crystal display device.

2. Background of the Invention

Generally, liquid crystal display devices comprise a liquid crystal cellwherein a liquid crystal layer is sandwiched between two glasssubstrates, a drive circuit for driving the liquid crystal, a controlcircuit for controlling liquid crystal display, and a power supplycircuit for supplying the power and input signals. Currently, connectionof the liquid crystal cell and the drive circuit is performed mostcommonly by a TAB system that uses TAB technology to batch connect thetape carrier package (TCP) whereon the semiconductor chip for liquidcrystal drive is mounted.

A typical example of a prior art liquid crystal display wherein the TABsystem is utilized is shown in FIG. 20. The output terminals of TCP 4whereon semiconductor chip 3 for liquid crystal drive is mounted areconnected by an anisotropic conductive film, for example, to the inputterminals disposed along one side 2 of liquid crystal cell 1. Circuitboard 6 whereon electronic components 5; e.g., chip capacitors,resistors and controllers, other than said semiconductor chip for liquidcrystal drive are mounted is connected to the input terminals of TCP 4by soldering. Input cable 7 made from a flexible film wiring sheet, forexample, is connected to circuit board 6, whereby said liquid crystaldisplay device is connected to the main electronic device unit and powerand signals are input.

However, since liquid crystal display devices manufactured by the priorart TAB method require at least TCP 3, circuit board 6 and input cable 7in addition to liquid crystal cell 1 as component parts, there are manyparts, which increases the number of connections for connecting them,thus increasing the number of production processes and labor, and thisin turn can increase production costs and lower production yield.Further, since input and output wiring is formed on each of said TCP,circuit board and input cable, the mounting area is greatly increased,thus increasing the size of the so-called frame member and resulting ina liquid crystal display device that is large overall. Also, a largerarea must be provided in the electronic device in order to mount theliquid crystal display device, thus greatly restricting product designand making it larger than necessary. Moreover, compared to the overallsize of the device, the area of the display screen is relatively smalland sufficient information cannot be displayed. This is particularly amajor obstacle in realizing greater compactness and functionality indeveloping portable electronic products such as cellular telephones.

Other methods for connecting liquid crystal cells and drive circuits arealso known such as the rubber connection method that uses conductiverubber, connection methods that use a heat seal or flexible film wiringsheet, and the chip on glass (COG) method that connects thesemiconductor chip for liquid crystal drive directly to the glasssubstrate surface of the liquid crystal cell. The rubber connectionmethod, though it does make assemble easy, uses conductive rubber toconnect the output of the drive circuit to the input of the liquidcrystal cell, and therefore it cannot readily accommodate tight pitches,and since the drive circuit is disposed behind the liquid crystal cell,it is difficult to attach a backlight, thus increasing the thickness ofthe entire device.

The COG method that is now being used mounts the semiconductor chip forliquid crystal drive directly by patterning input/output wiring andelectrodes from transparent indium tin oxide (ITO) on the peripheralsurface of the glass substrate from which the liquid crystal cell isconfigured. Therefore, though the number of parts and connections issmall, the wiring must be thick and the mounting area increased due tothe relatively high electrical resistance of ITO, thus greatlyincreasing the frame area. Further, since the input/output wiring andthe input bus wiring are disposed as cross wiring on the same surface,the production cost is extremely high.

The purpose of the invention is to provide a compact liquid crystaldisplay device that reduces production costs while improvingproductivity by using fewer parts and reducing the number ofconnections, whereby the production process is simplified and labor isreduced, and that also can accommodate the miniaturization of electronicdevices by reducing the mounting surface area and the frame surfacearea.

Another purpose of the invention is to offer a structure whereby theassembly operation can be simplified, labor reduced, processesautomated, productivity improved and production costs reduced by meansof a relatively simple configuration in cases wherein the liquid crystaldisplay device is mounted in an electronic device, while alsofacilitating the mounting of the liquid crystal display device in acompact space.

Yet another purpose of the invention is to offer a compact, easy-to-use,highly-functional electronic device with superior portability and thatis capable of expanding the display surface area and the amount ofinformation displayed while providing a high freedom of product designand compactness particularly in electronic devices equipped with aliquid crystal display device.

SUMMARY OF THE INVENTION

According to the first profile of the invention, a liquid crystaldisplay device is offered that has a liquid crystal cell and a circuitboard whereon the semiconductor chip for liquid crystal drive and all orsome of the other electronic components necessary for drive and controlof the liquid crystal are mounted and wherein the input terminals ofsaid liquid crystal cell and the output terminals of said circuit boardare connected directly.

By mounting all or some of the other electronic components required bythe circuit for driving and controlling the liquid crystal as well asthe semiconductor chip for liquid crystal drive on one circuit board asrequired and connecting their output directly to the liquid crystal cellinput, the number of components can be reduced, whereby the number ofconnections can be reduced and the labor required for assembly reduced.Therefore, production costs can be reduced and productivity can beimproved. Also, since the area of the wiring pattern is greatly reducedtogether with the connection locations, the area of the circuit boarditself and the overall mounting area can be reduced. Further, since theliquid crystal cell and the circuit board are disposed on nearly thesame plane, the entire liquid crystal display device can be configuredsmaller and thinner.

In addition to chip capacitors, resistors, etc., as the other electroniccomponents, the controllers and other electronic components necessaryfor control of liquid crystal display can also be mounted on saidcircuit board. Also, in the case of a large liquid crystal cell, aplurality of groups of semiconductor chips for liquid crystal drive andother electronic components can be mounted on one circuit board andconnected directly to the liquid crystal cell. Also, an anisotropicconductive film, adhesive or other methods from the prior art can beused as the means for connecting the output terminals of the circuitboard directly to the input terminals of the liquid crystal cell.

Commonly used hard materials such as composite materials of glass fiber,aramid fibers or a combination of the two with epoxy resin, polyimideresin or bismaleid triazine (BT) resin, or epoxy resin, polyimide resinor BT resin used alone, mixed or in a compound are easy to handle assubstrate materials for circuit boards. Since these substrate materialsare cheaper than TCP film materials, circuit boards can be produced atlower cost, thus lowering the production cost of liquid crystal displaydevices.

According to the second profile of the invention, a mounting structurefor the liquid crystal display device is offered whereby, in order tomount the liquid crystal display device, which has a liquid crystal celland a circuit board whereon the semiconductor chip for liquid crystaldrive and all or some of the other electronic components for driving andcontrolling the liquid crystal are mounted and wherein the inputterminals of said liquid crystal cell and the output terminals of saidcircuit board are connected directly, in the main unit, the inputterminals of said circuit board and the terminals of said main unit areconnected via a rubber connector made from conductive rubber.

By means of this invention, since the input terminals of the circuitboard can have a relatively wide pitch, e.g., 0.5 to 1 mm, a connectormade of conductive rubber can be easily used to connect it to theterminals of the main unit which supplies the power and input signals.Therefore, the liquid crystal display device can be easily mounted andit is possible to automate the assembly operation by means of robots,etc.

By forming the input terminals of the circuit board on the back side ofthe output terminals at this time, the surface area of the circuit boardcan be made smaller, and therefore the liquid crystal display device canbe made more compact, thus requiring a smaller space for mounting.

If the rubber connector is held in a compressed state between thecircuit board and the main unit when the liquid crystal display deviceis fixed in the main unit by a fixing means, installation of the liquidcrystal display device is simplified and conductivity between the inputterminals of the circuit board and the terminals of the main unit can beeasily maintained. It is desirable to configure this fixing means intothe case of the main unit in order to reduce the number of components.

According to the third profile of the invention, an electronic device isoffered that is equipped with a display means comprising a liquidcrystal display device having a liquid crystal cell and a circuit boardwhereon are mounted the semiconductor chip for liquid crystal drive andall or some of the other electronic components necessary for driving andcontrolling the liquid crystal and wherein the input terminals of saidliquid crystal cell are connected directly to the output terminals ofsaid circuit board.

By means of the invention, by mounting a liquid crystal display devicethat is compact and reduces production costs as described above, thefreedom of design of the electronic device is improved, thus making itpossible to offer electronic devices that are compact and are suited toportability at low cost. Moreover, since the size of the display screencan be made large in relation to the size of the device, it is easier toread and more information can be displayed, thus improving thefunctionality and ease of use of the electronic device.

The input terminals of the circuit board and the main electronic deviceunit can be connected via a flexible cable. In this case, by selectingthe appropriate cable shape, dimensions, material and flexibility andsetting the appropriate location for connection of the cable to theelectronic device, the liquid crystal display device can be mountedunder optimum conditions. Also, the input terminals of the circuit boardand the terminals of the electronic device can be connected directly bysoldering or by an anisotropic conductive film. Further, a connector canbe provided on the electronic device and the circuit board can beconnected either directly to this or by joining via the above-mentionedcable.

According to another embodiment of this invention, the input terminalsof the circuit board and the terminals of the electronic device can beconnected via a rubber connector made from conductive rubber. In thiscase, by fixing the liquid crystal display device in the electronicdevice via a fixing means and maintaining the rubber connector betweenthe circuit board and the main electronic device unit in a compressedstate, assembly is simplified. Further, if said fixing means is the caseof the electronic device, the number of components can be reduced. Ifthe input terminals of the circuit board are formed on the back side ofthe output terminals, not only can the surface area of the circuit boardcan be reduced, but the rubber connector can be reliably compressed andheld in the desired location without a special means or member if saidfixing means presses the liquid crystal display device against the mainelectronic device unit on the periphery of the liquid crystal cell towhich the circuit board is connected.

BRIEF DESCRIPTION OF THE DRAWINGS

Objects and attainments together with a fuller understanding of theinvention will become apparent and appreciated by referring to thefollowing description and claims taken in conjunction with theaccompanying drawings.

Below, the preferred embodiments of the invention are described indetail by referring to the attached drawings.

FIG. 1 is a perspective view showing the first embodiment of the liquidcrystal display device of the invention, and FIG. 2 is a cross sectionof its principal parts.

FIG. 3 is a perspective view showing the second embodiment of the liquidcrystal display device of the invention, and FIG. 4 is a cross sectionof its principal parts.

FIG. 5 and FIG. 6 are perspective views showing the third and fourthembodiments, respectively, of the liquid crystal display device of theinvention.

FIG. 7 is a perspective view showing the fifth embodiment of the liquidcrystal display device of the invention, and FIG. 8 is a cross sectionof its principal parts.

FIG. 9 is a perspective view showing the sixth embodiment of the liquidcrystal display device of the invention, and FIG. 10 is a cross sectionof its principal parts.

FIG. 11 is a perspective view showing the mounting structure of theliquid crystal display device of the invention, and FIG. 12 is a crosssection of the mounting structure.

FIG. 13 is a cross section showing a variation of the embodiment of themounting structure of the liquid crystal display device.

FIG. 14 is a rough perspective view showing a cellular telephone towhich the invention has been applied.

FIG. 15 is a cross section showing the principal parts of a cellulartelephone to which the liquid crystal display device of the firstembodiment has been applied.

FIG. 16 to FIG. 18 are cross sections showing the principal parts ofcellular telephones to which the liquid crystal display devices of thethird to the fifth embodiments have been applied, respectively.

FIG. 19 is an exploded perspective view showing the cellular telephoneto which the mounting structure in FIG. 13 has been applied.

FIG. 20 is a perspective view showing a liquid crystal display device ofthe prior art.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1 and FIG. 2 show the first embodiment of the liquid crystaldisplay device of the invention. Liquid crystal display device 10comprises liquid crystal cell 11 wherein a liquid crystal layer issandwiched between two glass substrates, circuit board 12 and inputcable 13. Circuit board 12 is connected directly to one side of liquidcrystal cell 11. In addition to semiconductor chip 14 for liquid crystaldrive, chip capacitors, chip resistors and other electronic components15 that make up the liquid crystal drive circuit are mounted on circuitboard 12. Either all or some of electronic components 15 necessary tomake up said drive circuit are selected and mounted.

Semiconductor chip 14 can be connected to circuit board 12 using thecommonly known anisotropic conductive film. In this embodiment,conductive grains comprising polystyrene grains 5 um in diameter andcoated with Ni--Au and anisotropic conductive film comprising anadhesive made up mainly of an epoxy adhesive are used and are bonded bythermocompression at a temperature of 180° C. and a pressure of 10gf/bump for 30 seconds. Of course, the free chip method wherein directface-down bonding to solder bumps, etc., is performed, a method thatconnects the semiconductor chip bumps directly, and other known methodsfrom the prior art can be used to connect semiconductor chip 14. Also,in this embodiment, electronic components 15 are connected to circuitboard 12 by soldering. In other embodiments, connection by means ofsilver paste or other conductive adhesive or anisotropic film ispossible, and these are effective when mounting small chip capacitorsand other electronic components.

As is well shown in FIG. 2, output terminals 16 of circuit board 12 areformed on the side opposite semiconductor chip 14 and are connected tooutput wiring 18 of said semiconductor chip via through-hole 17. LCDterminals 20 formed from transparent ITO electrodes, for example, andconnected to that electrode pattern are formed on the inside surface onthe periphery of lower glass substrate 19 of liquid crystal cell 11.Circuit board 12 is located such that its output terminals 16 arepositioned opposite corresponding LCD terminals 20 and anisotropicconductive film, (ACF) 21 is sandwiched between them, and they areelectrically and mechanically connected all at once by thermocompressionusing a prescribed compression and heating tool. In this embodiment,conductive grains comprising polystyrene grains 10 μm in diameter andcoated with Ni--Au and an adhesive made up mainly of epoxy adhesive areused as the anisotropic conductive film 21, and connection was performedunder the compression bonding conditions of a temperature of 170° C. ata pressure of 3 MPa for 20 seconds. In another embodiment, an adhesivecan be used alone in place of the anisotropic conductive film and outputterminals 16 of circuit board 12 can be connected directly to LCDterminals 20 such that they are electrically conductive. In thisconnection method, the danger of short-circuits due to conductive grainsresulting from the use of an anisotropic film is eliminated andconnection can be made using a tighter pitch.

Input terminals 22 of circuit board 12 are connected using wiringpattern 23 of input cable 13 and anisotropic conductive film 24. In thisembodiment, anisotropic conductive film 24 comprising conductive grainsmade up of nickel metal grains 3 to 10 μm in diameter and an adhesivewhose main component is an epoxy adhesive is used, and connection isperformed by compression bonding at a temperature of 170° C. and apressure of 3 MPa for 20 seconds. By using an anisotropic conductivefilm in this manner, fine connection pitches can be accommodated, thusfacilitating high density mounting. Also, circuit board 12 and inputcable 13 can be connected by hand or by machine using conventionalsoldering. Further, silicon resin, acrylic resin, urethane resin orother molded material can coated on the connections of circuit board 12and input cable 13 for moisture protection, dust protection, andprotection from damage due to mechanical contact. This kind of moldedmaterial can also be applied in a similar manner to the connectionbetween above-mentioned circuit board 12 and liquid crystal cell 11 andthe connection of semiconductor chip 14 and electronic components 15 tocircuit board 12.

In this embodiment, a circuit board wherein copper foil is coated in athickness of 9 μm on both sides of a 0.1-mm-thick glass epoxy substrate,wiring patterns are formed by etching, and conductivity of both surfacesis achieved via through-holes is used as circuit board 12. It isdesirable to coat the wiring pattern surfaces with Ni--Au to preventmigration or other problems. A glass epoxy substrate 0.05 to 0.8 mmthick can be used. A composite material wherein aramid fibers or acombination of aramid fibers and glass fibers is used in place of glassfibers with polyimide resin or bismaleid triazine (BT) resin in place ofepoxy resin can be used as the substrate for circuit board 12, or epoxyresin, polyimide resin or BT resin used either alone or in a compositematerial can be used. Further, instead of a two-sided wiring board as inthis embodiment, a one-sided wiring board or 3-layer, 4-layer or othermultiple-layer substrate can be used as circuit board 12. If a one-sidedwiring board is used, the output terminals must be formed on the samesurface the semiconductor chip for liquid crystal drive is mounted, butthe substrate cost will be cheaper. If a multiple-layer substrate isused, a gland layer can be employed and countermeasures for noise suchas making the power source wiring pattern thicker can be easilyimplemented.

As described here, by mounting all or some of the chip capacitors, chipresistors and other electronic components required by the drive circuitfor the liquid crystal, as well as the semiconductor chip for liquidcrystal drive, on one circuit board according to this invention,, thearea required for mounting these electronic components can be minimizedand the area of the wiring pattern can be minimized, thus making itpossible to reduce the overall mounting area. Further, since the circuitboard is connected to the periphery of the liquid crystal panel on thesame plane, the frame area can be made smaller, thus facilitating asmaller, thinner liquid crystal display device overall and realizing amore compact configuration. Also, since the circuit board is connecteddirectly to the input side of the liquid crystal cell and the powersource and input signals are supplied from the input cable, there arefewer parts and the number of connections is reduced, thus making itpossible to reduce assembly labor, reduce production costs and improveproductivity.

FIG. 3 and FIG. 4 show the second embodiment of the liquid crystaldisplay of the invention. This embodiment differs from theabove-mentioned first embodiment in that controller 25 for controllingliquid crystal display is also mounted on circuit board 12. Controller25 is connected using an anisotropic conductive film as explained abovefor semiconductor chip 14 for liquid crystal drive, but of course it canbe connected by other prior art methods using solder or adhesive. Also,in addition to controller 25, all or some of the other electroniccomponents that make up the control circuit for controlling liquidcrystal display can be mounted on circuit board 12.

By mounting the electronic components for controlling liquid crystaldisplay as well as the electronic components for liquid crystal drive onone circuit board according to this embodiment, the area for mountingthe semiconductor chip and the other electronic components and the areaof the wiring pattern required for forming the drive and controlcircuits can be minimized. By this means, the area of the circuit boardcan be made smaller and the entire liquid crystal display device canhave a more compact configuration. Also, by being able to reduce thenumber of components and make the substrate area smaller, costs can befurther reduced.

FIG. 5 shows the third embodiment of the liquid crystal display deviceof the invention. In this embodiment, the input cable of the firstembodiment is eliminated and input terminals 22 are formed in a straightline at a fixed pitch on the back side of circuit board 12 whereonsemiconductor chip 14 for liquid crystal drive and other electroniccomponents 15 are mounted. Input terminals 22 are formed in a shape, forexample, suited to direct connection via soldering, anisotropicconductive film or adhesive to the terminals for inputting power andsignals from the main electronic device unit wherein the liquid crystaldisplay device is mounted. Input terminals 22 are connected to the inputside of semiconductor chip 14 via through-holes provided in circuitboard 12. Of course, input terminals 22 can be disposed on the samesurface of circuit board 12 as said semiconductor chip.

By eliminating the input cable according to this embodiment, the numberof parts can be reduced and costs lowered even more. Further, since theconnection area with the electronic device in which the liquid crystaldisplay device of this embodiment is mounted can be made smaller, themain electronic device unit as well as the liquid crystal display devicecan be made more compact.

FIG. 6 shows the fourth embodiment of the liquid crystal display deviceof the invention. Input terminals 22 are formed along one edge ofcircuit board 12 of this embodiment opposite liquid crystal cell 11.Input terminals 22 are formed in the shape of through-holes cut in halfby cutting a plurality of half-circle notches 26 at fixed intervalsalong said edge of circuit board 12 and affixing a conductive materialinside said notches. By configuring them in this way, well-shaped bumpscan be formed when soldering input terminals 22, thus simplifyingsoldering and making the connection highly reliable.

In another embodiment, input terminals 22 can be formed by eliminatingnotches 26 and simply applying conductive material to the edge ofcircuit board 12. Input terminals 22 can also be extended to the backside of circuit board 12.

FIG. 7 and FIG. 8 show the fifth embodiment of the liquid crystaldisplay device of this invention. Connection member 27 is provided byprotruding the middle part of circuit board 12 opposite liquid crystal11. Connection member 27 is formed into a rectangular shape whosedimensions are set such that it can be inserted directly into a femaleconnector on the main electronic device unit, and input terminals 22 areformed in a fixed pitch on the top surface. Depending on their numberand the dimensions of said connector and circuit board, input terminals22 can be formed on both sides of connection member 27. Depending on thesize and type of the connector, the one edge of circuit board 12 whereoninput terminals 22 are disposed can be inserted directly into theconnector as the connection member.

Since the electrical connection is achieved by merely insertingconnection member 27 of circuit board 12 joined as a single unit withliquid crystal cell 11 into the connector, mounting of the liquidcrystal display device and assembly of electronic device are simplified.Also, since the liquid crystal display device can be easily removedafter mounting, no special tools or techniques are required and anyonecan replace it, thus simplifying operation, particularly in electronicdevices requiring regular maintenance.

FIG. 9 and FIG. 10 show a variation of the fifth embodiment describedabove. In this embodiment, circuit board 12 is connected to the insidesurface on the edge of the upper glass substrate of liquid crystal cell11. Circuit board 12 is provided with connection member 27 as in thecircuit board in FIG. 7, and output terminals 16 and input terminals 22are formed on the surface whereon semiconductor chip 14 for liquidcrystal drive is mounted. By disposing output terminals 16 on thesurface whereon semiconductor chip 14 is mounted according to thisembodiment, through-holes do not need to be made on the output sidewhere a fine terminal pitch is required, thus making it easier andcheaper to manufacture circuit board 12.

FIG. 11 and FIG. 12 show a preferred configuration for mounting theliquid crystal display device of the invention as a means of display inelectronic devices, etc. Light guide 30a of backlight means 30 isdisposed between liquid crystal display device 10 of this embodiment andmain unit substrate 29 whereon it is mounted, and square frame-shapedattachment member 31 is affixed on top of these. LED 30b is disposed onmain unit substrate 29 immediately to the side of said light guide asthe light source of backlight means 30. Attachment member 31 is open onone side such that circuit board 12 of liquid crystal display device 10can partially extend outside of it, and the remaining three sides eachhave two feet 32 protruding down. Feet 32 of attachment member 31 areinserted in the six holes 33 provided in said main unit substrate, andthen by bending the ends of the feet, liquid crystal display device 10and light guide 30a are fixed in place such that they are pressedagainst main unit substrate 29. In this embodiment, the light guide andLED of backlight means 30 are fixed separately, but in anotherembodiment, a backlight means is used wherein the light guide and LEDare one unit, which can be installed like the light guide in thisembodiment.

Reinforcing ribs 34 are formed on the top surface of attachment member31 to prevent its deformation, and cushions 35, 36 and 37 made fromrubber, plastic sheet, two-sided tape or other adhesive are disposed atthe positions of said ribs between attachment member 31 and liquidcrystal cell 11, between the liquid crystal cell and light guide 30a andbetween light guide 30a and main unit substrate 29. Attachment member 31has a large rectangular window 38 on its top surface to facilitateviewing of the display screen of liquid crystal display device 10.

Some as in the embodiment shown in FIG. 9 and FIG. 10, circuit board 12is connected to the inside surface of upper glass substrate 40 of liquidcrystal cell 11 in liquid crystal display device 10. Semiconductor chip14 for liquid crystal drive is mounted and the output terminals areformed on the top surface of circuit board 12. The chip capacitors andother electronic components 15 required by the liquid crystal drivecircuit are mounted and the input terminals 22 are formed on the bottomsurface of circuit board 12. Terminals 41 for supplying power and inputsignals to liquid crystal display device 10 are provided on the topsurface of main unit substrate 29. Rubber connector 42 comprising aknown conductive rubber, for example, wherein conductive members andinsulation members are alternated is sandwiched between main unitsubstrate 29 and circuit board 12, whereby input terminals 22 and outputterminals 41 are electrically connected. Since the pitch of inputterminals 22 of circuit board 12 can be relatively large at 0.5 to 1 mm,a rubber connector is sufficient for connection.

According to the invention, circuit board 12 and rubber connector 42 arelined up, and assembly is performed such that the liquid crystal displaydevice is sandwiched between the attachment member and the main unitsubstrate. Therefore, rubber connector 42 is retained in the compressedstate between circuit board 12 and main unit substrate 29. Sinceassembly of the liquid crystal display device is simplified like this,it is possible to automate the mounting process of the liquid crystaldisplay device in the production line of the electronic device by usingrobots, etc., thus improving productivity and lowering production costs.

FIG. 13 shows a variation of the mounting structure for the liquidcrystal display device shown in FIG. 11 and FIG. 12 described above. Inthis variation of the embodiment, attachment member 31 is made frommolded plastic, for example, and it is formed as one unit with hookscapable of elastic deformation at the ends of feet 32. Feet 32 ofattachment member 31 are inserted in holes 33 of main unit substrate 29,and hooks 43 are secured to the back side of said main unit substrate bya one-touch operation. By this means, the liquid crystal display devicecan be assembled more easily.

In each of the embodiments in FIG. 11 to FIG. 13, square frame-shapedattachment member 31 was used to secure the liquid crystal displaydevice to the main unit substrate, but according to this invention, ifrubber connector 42 can be held in a compressed state between circuitboard 12 and main unit substrate 29, attachment means with variousstructures and shapes can be used. In another embodiment, when theliquid crystal display device is driven by a plurality of semiconductorchips, the plurality of circuit boards whereon each of the semiconductorchips is mounted can be connected directly to the liquid crystal cell,and the input terminals of each of the circuit boards can each beconnected via a rubber connector. It is also possible to mount aplurality of semiconductor chips for liquid crystal drive on one circuitboard and connect this directly to the liquid crystal cell, while theinput terminals of said circuit board can be connected to the main unitvia a rubber connector for each semiconductor chip.

The liquid crystal display device of the invention can be installed invarious electronic devices and used, and it is particularly effective inelectronic devices requiring portability. As one example of this kind ofelectronic device, FIG. 14 shows a cellular telephone 44 wherein liquidcrystal display device 10 of the invention is installed. In theembodiment shown in FIG. 15, liquid crystal display device 10 of thefirst embodiment shown in FIG. 1 and FIG. 2 is mounted on main unitsubstrate 46 of cellular telephone 44. Liquid crystal cell 11 is securedto a prescribed location on main unit substrate 46 by using an adhesiveon attachment member 47, which is a cushion that uses silicon rubber orfoam urethane as a base material, or two-sided tape that uses anon-woven base material. Output terminals 48 for supplying power andinput signals to liquid crystal display device 10 are formed on mainunit substrate 46, and female connector 49 is provided for connection tosaid terminals. Liquid crystal display device 10 is connected to thepower source side of main unit substrate 46 by inserting input cable 13into connector 49, from which it can be removed.

In this embodiment, liquid crystal display device 10 is connected tomain unit substrate 46 via input cable 13 as described above, andtherefore the freedom of design of the electronic device is improved,and by selecting the appropriate shape, dimensions, material andflexibility of said cable and setting the appropriate layout for theconnector, the liquid crystal display device can be installed in theelectronic device under ideal conditions. Moreover, according to thisinvention, the liquid crystal display device can be made smaller andthinner and the frame area reduced in size, and therefore not only canthe electronic device in which it is installed be made more compact, thedisplay screen can be made larger. Therefore, a compact, easy-to-usecellular telephone with superior portability can be realized whosedisplay is easy to read and can display much information.

In the embodiment in FIG. 16, liquid crystal display device 10 of thethird embodiment shown in FIG. 5 is installed in cellular telephone 44.Input terminals 22 of circuit board 12 are connected directly to outputterminals 48 of main unit substrate 46 via anisotropic conductive film50. In this embodiment, conductive grains made up of nickel metal grains3 to 10 μm in diameter and a thermosetting adhesive whose main componentis an epoxy adhesive is used as the anisotropic conductive film, andbonding is performed by compression at a temperature of 170° C. and apressure of 3 MPa for 20 seconds. Of course, other anisotropicconductive films can be used and bonding performed under differentconditions, and other prior art connection methods can be used.

In this embodiment, an anisotropic conductive film is used toelectrically connect the circuit board and the main unit substrate, andtherefore it can sufficiently accommodate the terminal pitch. It canreduce the effect of heat, etc., on the main unit substrate or liquidcrystal display device when both are subjected to thermocompression. Inthis embodiment, as well, the cellular telephone is made more compactand the display screen is made bigger, thus greatly improving ease ofuse.

In the embodiment in FIG. 17, liquid crystal display device 10 of thefourth embodiment shown in FIG. 6 is mounted in cellular telephone 44.As described above, input terminals 22 are formed on one edge of circuitboard 12 and can be connected directly to output terminals 48 of mainunit substrate 46 by soldering. According to this embodiment, solderconnections 51 are relatively small, and therefore the area andthickness required for connection between circuit board 12 and main unitsubstrate 46 can be made small, thus allowing the cellular telephone tobe thinner and more compact.

In the embodiment in FIG. 18, liquid crystal display device 10 of thefifth embodiment shown in FIG. 8 is mounted in cellular telephone 44. Asin the embodiment in FIG. 15, female connector 49 connected to outputterminals 48 is provided on main unit substrate 46. By insertingconnection member 27 in connector 49, in which it can be inserted andremoved, input terminals 22 of circuit board 12 are connected to outputterminals 48 of main unit substrate 46. Therefore, according to thisembodiment, the liquid crystal display device can be easily installedand removed from the cellular telephone. For this reason, no specialtools or techniques are required and anyone can replace it when requiredin regular maintenance.

FIG. 19 shows cellular telephone 44 to which the mounting structure ofthe liquid crystal display device shown in FIG. 13 is applied. In thisembodiment, upper case 52 is equivalent to attachment member 31 in FIG.13 and window 53 corresponding to window 38 is located at the positionof liquid crystal display device 10, while the plurality of hooks 54, 55corresponding to feet 32 and hooks 43 in FIG. 13 are disposed around theinside of upper case 52 and in the vicinity of window 53. Substrate 56corresponding to main unit substrate 46 in FIG. 13 has a shape anddimensions generally corresponding to the inside shape of upper case 52.

In this embodiment, liquid crystal display device 10 is disposed at aprescribed position inside upper case 52, and then after the light guide(or backlight means 30 formed as one unit with the LED) and rubberconnector 42 are positioned on top of that, substrate 56 is fitted inplace such that it pushes these against the upper case. Notches 57 andholes 58 are formed in substrate 56 at positions corresponding to hooks54, 55 of upper case 52. Therefore, substrate 56 is fitted in place in asingle operation by aligning its terminals with rubber connector 42 andcausing notches 57 and holes 58 to engage corresponding hooks 54, 55 onupper case 52. Rubber connector 42 is retained in a compressed statebetween circuit board 12 and substrate 56.

By means of this embodiment, the number of component parts can bereduced and the number of connection locations and labor required forassembly can be reduced, thus simplifying the assembly operation ofcellular telephones and reducing their production costs. Further, asdescribed above in each of the embodiments, the cellular telephoneitself can made smaller and thinner and the amount of displayedinformation can be increased by enlarging the display screen, wherebyease of use and functionality are improved.

While the invention has been described in conjunction with severalspecific embodiments, it is evident to those skilled in the art thatmany further alternatives, modifications and variations will be apparentin light of the foregoing description. Thus, the invention describedherein is intended to embrace all such alternatives, modifications,applications and variations as may fall within the spirit and scope ofthe appended claims.

What is claimed is:
 1. A liquid crystal display device, comprising:a liquid crystal cell containing a liquid crystal and having a plurality of input terminals; a circuit board directly connected to said liquid crystal cell and having a plurality of input terminals and a plurality of output terminals, said plurality of output terminals being electrically connected to said plurality of input terminals of said liquid crystal cell; drive means, mounted on said circuit board, for driving said liquid crystal; and at least one electronic component, mounted on said circuit board, for controlling said liquid crystal cell.
 2. The liquid crystal display device of claim 1, further comprising an anisotropic conductive film coupling between said plurality of input terminals of said liquid crystal cell and said plurality of output terminals of said circuit board.
 3. The liquid crystal display device of claim 1, wherein said liquid crystal cell is connected to said circuit board by adhesion.
 4. The liquid crystal display device of claim 1 wherein said circuit board is made from a substrate material which comprises:a selected material of glass fibers, aramid fibers and a composite of glass fibers and aramid fibers, and a selected material of epoxy resin, polyimide resin and bismaleid triazine resin.
 5. The liquid crystal display device of claim 1 wherein said circuit board is made from a substrate material comprising a selected material of epoxy resin, polyimide resin, bismaleid triazine resin and a compound of epoxy resin, polyimide resin and bismaleid triazine resin.
 6. The liquid crystal display device of claim 1,wherein said circuit board comprises a first surface and a second surface opposite to the first surface; wherein said drive means is mounted on the first surface of said circuit board; and wherein said plurality of input terminals of said circuit board are disposed on the second surface of said circuit board.
 7. The liquid crystal display device of claim 1 wherein said plurality of input terminals of said circuit board are formed along an edge of said circuit board.
 8. The liquid crystal display device of claim 7 wherein said plurality of input terminals of said circuit board are formed in a form of a plurality of half-cut through holes.
 9. The liquid crystal display device of claim 1,wherein said circuit board comprises a connection member extended from said circuit board for directly inserting into a receptacle of a main device unit; and wherein said plurality of input terminals of said circuit board comprises a plurality of input terminals disposed on a surface of said connection member.
 10. A mounting structure for a liquid crystal display device, comprising:a main unit having a plurality of output terminals for supplying power supply and input signals; a liquid crystal display device mounted in said main unit, comprising:a liquid crystal cell containing a liquid crystal and having a plurality of input terminals, a circuit board directly connected to said liquid crystal cell and having a plurality of input terminals and a plurality of output terminals, said plurality of output terminals being electrically connected to said plurality of input terminals of said liquid crystal cell, drive means, mounted on said circuit board, for driving said liquid crystal, and at least one electronic component, mounted on said circuit board, for controlling said liquid crystal cell; and a conductive rubber connector coupling between said plurality of output terminals of said main unit and said plurality of input terminals of said circuit board for electrically connecting said main unit output terminals to said circuit board input terminals.
 11. The liquid crystal display device mounting structure of claim 10,wherein said circuit board comprises a first surface and a second surface opposite to the first surface; wherein said drive means is mounted on the first surface of said circuit board; and wherein said plurality of input terminals of said circuit board are disposed on the second surface of said circuit board.
 12. The mounting structure of claim 11, wherein said at least one electronic component is mounted on said second surface of said circuit board.
 13. The mounting structure of claim 10, further comprising attachment means for securing said liquid crystal display device to said main unit such that said rubber connector is maintained in a compressed state between said circuit board and said main unit.
 14. The mounting structure of claim 13 wherein said attachment means comprises a case housing said main unit.
 15. An electronic device, comprising:a main unit having a plurality of output terminals for supplying power supply and input signals; display means, mounted in said main unit, for displaying information, said display means comprising a liquid crystal display device which comprises:a liquid crystal cell containing a liquid crystal and having a plurality of input terminals, a circuit board directly connected to said liquid crystal cell and having a plurality of input terminals for receiving said power supply and input signals and a plurality of output terminals, said plurality of output terminals being electrically connected to said plurality of input terminals of said liquid crystal cell, drive means, mounted on said circuit board, for driving said liquid crystal, and at least one electronic component, mounted on said circuit board, for controlling said liquid crystal cell.
 16. The electronic device of claim 15, further comprising a flexible cable coupled between said plurality of input terminals of said circuit board and said plurality of output terminals of said main unit.
 17. The electronic device of claim 15 wherein said plurality of input terminals of said circuit board and said plurality of output terminals of said main unit are coupled by soldering.
 18. The electronic device of claim 15, further comprising an anisotropic conductive film coupled between said plurality of input terminals of said circuit board and said plurality of output terminals of said main unit.
 19. The electronic device of claim 15,wherein said main unit comprises a connector coupled to said plurality of output terminals of said main unit; and wherein said plurality of input terminals of said circuit board are removably coupled to said connector of said main unit.
 20. The electronic device of claim 15, further comprising a conductive rubber connector coupled between said plurality of input terminals of said circuit board and said plurality of output terminals of said main unit.
 21. The electronic device of claim 20, further comprising attachment means for securing said liquid crystal display device to said main unit such that said rubber connector is maintained in a compressed state between said circuit board and said main unit.
 22. The electronic device of claim 21, wherein said attachment means comprises a case housing said main unit.
 23. The electronic device of claim 21,wherein said circuit board comprises a first surface and a second surface opposite to the first surface; wherein said plurality of output terminals of said circuit board are disposed on the first surface, and said plurality of input terminals of said circuit board are disposed on the second surface of said circuit board.
 24. A liquid crystal display device, comprising:a liquid crystal cell containing a liquid crystal and having a plurality of input terminals; a circuit board directly connected to said liquid crystal cell and having a plurality of input terminals and a plurality of output terminals, said plurality of output terminals being electrically connected to said plurality of input terminals of said liquid crystal cell; a semiconductor chip mounted on said circuit board, for driving said liquid crystal; and at least one electronic component, mounted on said circuit board, for controlling said liquid crystal cell.
 25. A mounting structure for a liquid crystal display device, comprising:a main unit having a plurality of output terminals for supplying power supply and input signals; a liquid crystal display device mounted in said main unit, comprising:a liquid crystal cell containing a liquid crystal and having a plurality of input terminals, a circuit board directly connected to said liquid crystal cell and having a plurality of input terminals and a plurality of output terminals, said plurality of output terminals being electrically connected to said plurality of input terminals of said liquid crystal cell, a semiconductor chip mounted on said circuit board, for driving said liquid crystal, and at least one electronic component, mounted on said circuit board, for controlling said liquid crystal cell; and a conductive rubber connector coupling between said plurality of output terminals of said main unit and said plurality of input terminals of said circuit board for electrically connecting said main unit output terminals to said circuit board input terminals.
 26. An electronic device, comprising:a main unit having a plurality of output terminals for supplying power supply and input signals; a display device, mounted in said main unit, for displaying information, said display device comprising a liquid crystal display device which comprises:a liquid crystal cell containing a liquid crystal and having a plurality of input terminals, a circuit board directly connected to said liquid crystal cell and having a plurality of input terminals for receiving said power supply and input signals and a plurality of output terminals, said plurality of output terminals being electrically connected to said plurality of input terminals of said liquid crystal cell, a semiconductor chip, mounted on said circuit board, for driving said liquid crystal, and at least one electronic component, mounted on said circuit board, for controlling said liquid crystal cell. 